Additionally, whenever you kill a level-appropriate mob there's a chance that it will throw out piles of gold similar to the Scarlet Treasurers in the Scarlet Halls instance. If you kill the mob while swimming, the gold coins will spawn on the ground beneath you. The proc rate is 10% and there seems to be an ICD of 5 minutes between procs. The gold coin piles usually have between 10 to 30 gold, closer to 25 usually. These piles are lootable by anyone not just trinket-wearers, so loot quickly.